I have a Cobb catted DP and any loss of power is so negligible that you'd never notice it. Even with the cat, my car is louder than I really wanted so I can't see that it contributes much to the sound. We've got too many beautiful hard-core driving roads around here to not appreciate what Ma Nature gave us. I don't mind trying to do my part to keep it that way. I hope that my grandson can flog his brand new 2036 WRX around the same roads with the same views as I enjoy.

Unfortunalty, the proof I have of the difference it makes was on a website that went down a few months ago. I'm sure some of the older folks here will remember it. Anyways, this guy pieced together his own turboback. He did a dyno run with and without a good quality high flow cat. The difference? 1whp. Just don't go elcheapo on the cat.

If i was gonna do a turboback exhaust and a catless up pipe, should i just get a downpipe with one cat to save the CEL from comin on, or should i screw cats all together and just get 02 Simulators??? i know im gonna get better performance with no cats b/c theres better flow, but how much really??

the uppipe gives CEL problems SOMETIMES but not always. They can be solved by a manual fix or a piggyback like a COBB AP or TXS UTEC. Changing the downpipe is for power, the rest of it is just for sound. There wouldn't be much point in changing just your uppipe.

If you get something like a COBB AP, you don't have to worry about the CELs from the cats being taken out, it'll deal with em for you

just make sure if you have a wagon that you consider one cat or one of the quieter systems out there. cause i have a wagon and i had a bosal twintip with resonator and i could barely here anything inside. it was way loud. I put a injen exhaust on and am catless and it isn't nearly as bad but i can still here it for sure.